Method of controlling the elasticity of an elastic-metal stringing



April 7, 1925. 1,532,703

\ A. LARNED Patented pr. "7, 192.5.

UNITED 'sTATEs- PATENT oFFIcE.

WILIJIAM Au LARNED,-F SUMMIT, NEW J'ERSEY, ASSIGNOR TO THE DAYTON STEE RACQUET COMPANY, OF DAYTON, OHIO, A- CORPORATION OF OHIO.

METHOD OF CONTROLLING THE ELAS'I'ICITY OF AN ELAS'TIC-METAL STRINGING.

Application med July 17, 1923. semi No. iesaoea.

To all 'who/m,1 'tfnbaxy concern:

v Be it known that I, WILLLAM A. LARNED, a citizen of the United States, residing at Summit,.in the county. of Union and State 57 of New IJersey, have invented certain new and useful Improvements in a Method of Controlling the Elasticity of. an Elastic Metal stringing, of which the following is a spccification.

This invention relates to new and useful improvements in an elastic metal stringlng, and has particular reference to a method of increasing the elasticity or playability of a metal tennis-racket stringing by varying the 15 lay or pitch of the latter and the diameter of the core around which it is wound.

It'is the object of the present inventlon to provide an elastc metal stringing rwhich has all the advantages .of gut in the way of large -elasticity and a small amount of elongation, by lengthening the lay of they wire and increasing the diameter of the core. This method of producing an elastic metal stringing also increases and economizes production.

In the accompanying drawings illustrating my invention, Figure 1 is a perspective view of astandard lay, grouped, nine wire stringing wound around a No; 7 core. Figure 2 is a cross sectional view taken through said stringing on ithe line 2-2of Figure 1.

Figure 3 is a perspective view of a long lay,-

grouped, nine wire stringing wound around a No. y7 core. Figure 4 is a cross sectional view of the same taken on the line 4-4 of Figure 3. Figure 5 is a perspective view of the long lay stringing wound around-a No. core. of the same taken on the line 6 6 of Figure 5. Figure 7 is a perspective -view of the long lay stringing after the No. 10 core has been removed and the stringing stretched to the blocking point. Figure 8 is a cross sectional view taken on the line 8-8 of Figure 7. And Figure 9 is a plan view of a tennis racket containing my longlay stringing which has been wound around a No. 10 core. Throughout the specification and drawings, similar reference characters vdenote corresponding parts.

In a detailed description of the embodiment of my invention illustrated in the accompanying drawings, the numeral 1 desig- Fgure 6 is a cross sectional view nates a standard lay stringing consisting of three 1groups of three wires each, which have been wound around a No. 7 core designated by the numeralV 2. By changing the pitch of this stringing from 12 to 8, I produce they stringing 3 in Figure 3, which is known'as long lay. In Figures-3 and 4 I show this long lay stringing wound around a No.

core, which is designated by the numeral 4.

In Figure 5J a long lay stringing 5, similar to the stringing 3, is shown, except that it has been wound around a No. 10 core designated by the numeral 6. Figure 9 Jshows this stringing in atennis racket 7.

GIS

After the core had been' removed from i each one of the stringings 1, 3 and 5, and

they were stretched to the blocking point,

or a point beyond whichthey have a maintained elasticity due to the torsional reaction of the groups of .wires upon each other, tests .were made uponthem with an Olsen testing machine, whichtests showed that the elasticity and elongation or set of the stringing is directly controlled by the pitch or lay of the 'wire and the size of the core employed.

Under a pound blow, which is the' force with which a ball is hitby the average tenms player, the tests showed that the standardlayl stringing 1 wound 'around a No. 7 core, had an elasticity of 6.9% and an elongation of 17%. Under the same blow the long lay stringing 3 that .had been wound around a No. 7 core, had an elasticity of '62% and an elongationy of .8%.

Where a-No. 10 core had 'been used withthe' long lay stringing 5, the tests sho-Wed that under a blow of 60 pounds, the said stringing hadan elasticity of 8% and an elongation of 1.7%. Such a-stringing gave even better results than gut without its'disadvantages, for under a 60 pound blow the tests showed that the gut stringing only hadl an elasticity of 6.6% and -an elongation of 21%. V

It'is thus possible by increasing the itch or lay of the wire and the diameter o the core around which it is first wound, to. pro-3 duce an elasticv metal stringingl whose elas- .ticity or playability may be increased in certain instancesv beyond that of t, and having an elongation below that o the l'atter in those instances. Furthermore, by increasing the pitch or lay of the stringing, production has beenincreased and economized.

Having described my invention, I claim:

l. The method of controlling the elas-' ticity of a metal stringing comprising a number of Wires Wound together, Which consists in varying the pitch on Which the Wires are Wound' 2. The method of .controlling the elasticity of a metal stringing comprising a number of Wires that are first Wound around a core that is later removed, Which consists in varying the diameter of said core.

3. The method of controlling the elasticity of a metal stringing comprising,r a.

number of wires that are first Wound around msavos a core that is later removed, Which consists in varying the pitch on which the vvires are Wound and changing the diameter of said core.

4. The method of increasing the elasticity, and reducing the elongation, of a metal stringing comprising a number of Wires that are first Wound around a core that is later removed, which consists in increasing the lay of said Wires and the diameter of the core.

In testimony Whereof I have hereunto set my hand this 13th day of July, 1923.

WILLIAM A. LARNED,

Witness WATsoN WASHBURN. 

